Successful organ transplantation requires effective physiological and pharmacological intervention of the immune system of an organ recipient. Immunologic mechanisms are universal within the human species, but histocompatibility variations between organ donor and recipient may lead to rejection of donor tissue by stimulation of the recipient's immune system, except perhaps, in donor-recipient pairing of the monozygotic type. One approach to intervention of immune response in an organ transplant recipient, especially a recipient targeted for an allogenic graft, is by the use of immunosuppressive drugs. These drugs are used to prolong survival of transplanted organs in recipients in cases involving, for example, transplants of kidney, liver, heart, lung, bone marrow and pancreas.
There are several types of immunosuppressive drugs available for use in reducing organ rejection in transplantation. Such drugs fall within three major classes, namely: antiproliferative agents, antiinflammatory-acting compounds and inhibitors of lymphocyte activation.
Examples of the class of cytotoxic or antiproliferative agents are azathioprine, cyclophosphamide and methotrexate. The compound azathioprine acts by interrupting DNA synthesis through inhibition of purine metabolism. The compound cyclophosphamide is an alkylating agent which interferes with enzyme actions and cell proliferation and interrupts DNA synthesis by binding to cellular DNA, RNA, and proteins. The compound methotrexate is a folic acid antagonist which interferes with nucleotide and protein synthesis. Drugs of the antiproliferative class may be effective immunosuppressives in patients with chronic inflammatory disorders and in organ transplant recipients by limiting cell proliferation. These drugs which abrogate mitosis and cell division have severe cytotoxic side effects on normal cell populations which have a high turn-over rate, such as bone marrow cells and cells of the gastrointestinal (GI) tract lining. Accordingly, such drugs often have severe side effects, particularly, lymphopenia, neutropenia, bone marrow depression, hemorrhagic cystitis, liver damage, increased incidence of malignancy, hair loss, GI tract disturbances, and infertility.
A second class of immunosuppressive drugs for use in transplantation is provided by compounds having antiinflammatory action. Representatives of this drug class are generally known as adrenal corticosteroids and have the advantage of not exerting globally systemic cytotoxic effects. These compounds usually act by preventing or inhibiting inflammatory responses or by reducing cytokine production, or by reducing chemotaxis, or by reducing neutrophil, macrophage or lymphocyte activation, or effector function. Typical examples of adrenal corticosteroids are prednisone and prednisolone which affect carbohydrate and protein metabolism as well as immune functions. Compounds of this class are sometimes used in combination with cytotoxic agents, such as compounds of the antiproliferative class because the corticosteroids are significantly less toxic. But the adrenal corticosteroids lack specificity of effect and can exert a broad range of metabolic, antiinflammatory and immune effects. Typical side effects of this class include increased organ-recipient infections and interference with wound healing, as well as disturbing hemodynamic balance, carbohydrate and bone metabolism and mineral regulation.
A third class of immunosuppressive drugs for use in organ transplantation is provided by compounds which are immunomodulatory and generally prevent or inhibit leukocyte activation. Such compounds usually act by blocking activated T-cell effector functions or proliferation, or by inhibiting cytokine production, or by preventing or inhibiting activation, differentiation or effector functions of platelet, granulocyte, B-cell, or macrophage actions. The cyclosporin family of compounds is the leading example of drugs in this class. Such compounds are polypeptide fungal metabolites which have been found to be very effective in suppressing helper T-cells so as to reduce both cellular and humoral responses to newly-encountered antigens. Cyclosporins alter macrophage and lymphocyte activity by reducing cytokine production or secretion and, in particular, by interfering with activation of antigen-specific CD4 cells, by preventing IL-2 secretion and secretion of many T-cell products, as well as by interfering with expression of receptors for these lymphokines on various cell types. Cyclosporin A, in particular, has been used extensively as an immunosuppressive agent in organ transplantation. Other microbial metabolites include cyclosporins such as cyclosporin B and cyclosporin G, and another microbial product known as FK-506. Cyclosporin A suppresses humoral immunity as well as cell-mediated reactions. Cyclosporin A is indicated for organ rejection in kidney, liver, heart, pancreas, bone-marrow and heart-lung transplants. Cyclosporin A is also useful in the treatment of autoimmune and inflammatory diseases, including rheumatoid arthritis, Crohn's disease, Graves, disease, severe psoriasis, aplastic anemia, multiple-sclerosis, alopecia areata, penphigus and penphigoid, dermatomyositis, polymyositis, Behcet's disease, uveitis, pulmonary sarcocidiosis, biliary cirrhosis, myasthenia gravis and atopic dermatitis.
Cyclosporins possess several significant disadvantages. While cyclosporins have provided significant benefits in organ transplantation, cyclosporins are non-specific immunosuppressives. Desirable immune reactions may be reduced against foreign antigens. Tolerated dosages do not provide complete suppression of rejection response. Thus, immunologic reactions to transplanted tissue are not totally impeded, requiring concomitant treatment with prednisone, methylprednisolone, and/or other immunosuppression agents, including monoclonal antibodies such as anti-CD3 or anti-CD5/CD7. Cyclosporins can produce severe side effects in many organ recipients, and show host-variable effects on the liver, kidney, the CNS and GI tract. Significant among the adverse side effects are damage to the kidney and liver, hyperplasia of gum tissue, refractory hypertension and increased incidence of infections and malignancy.
Thus, the need remains for efficacious and selective immunosuppressive drugs in organ transplantation, especially for grafts between less-than-perfectly matched donor-recipient pairs.
Prostaglandins and leukotrienes are lipid mediators produced in a variety of inflammatory disease states. Both are products of metabolism of arachidonic acid. Cyclooxygenases (COX-1 and COX-2) are the enzymes that catalyze the conversion of arachidonic acid to prostaglandins. 5-Lipoxygenase (5-LO) catalyzes the conversion of arachidonic acid to leukotrienes. Products of both pathways have been described in association with transplant rejection in humans and animal models. Excess production of these mediators may play a role in accelerating loss of the transplant function, particularly in the kidney. However, little research has been directed at determining direct effects of eicosanoids on tissue rejection.
Compounds which selectively inhibit cyclooxygenase-2 have been described. U.S. Pat. No. 5,380,738 describes oxazoles which selectively inhibit cyclooxygenase-2. U.S. Pat. No. 5,344,991 describes cyclopentenes which selectively inhibit cyclooxygenase-2. U.S. Pat. No. 5,393,790 describes spiro compounds which selectively inhibit cyclooxygenase-2. WO documents WO94/15932 describes thiophene and furan derivatives which selectively inhibit cyclooxygenase-2. WO94/27980 -describes oxazoles which selectively inhibit cyclooxygenase-2. WO95/00501 describes compounds which selectively inhibit cyclooxygenase-2. WO94/13635 -describes compounds which selectively inhibit cyclooxygenase-2. WO94/20480 describes compounds which selectively inhibit cyclooxygenase-2. WO94/26731 describes compounds which selectively inhibit cyclooxygenase-2. WO documents WO95/15316 describes pyrazolyl sulfonamide derivatives which selectively inhibit cyclooxygenase-2.
Compounds which affect leukotriene B.sub.4 receptors have been described. U.S. Pat. No. 5,384,318 describes substituted sulfonamides for the treatment of asthma. U.S. Pat. No. 5,246,965 describes aryl ethers as leukotriene B.sub.4 receptor antagonists.
Combined therapies of NSAIDs and other reagents are known in the art. Combination analgesics have been reported (W. Beaver, Am. J. Med., 77, 38 (1984)) although such combinations do not substantially reduce adverse effects. The combination of NSAIDs and steroids have been described. A combination of indomethacin, steroid and lipopolysaccharide has been reported for the treatment of spinal injury (L. Guth et al., Proc. Natl. Acad. Sci. USA, 91, 12308 (1994)). G. Hughes et al. describe combinations of corticosteroids with NSAIDs for the treatment of sunburn (Dermatology, 184, 54 (1992)). C. Stewart et al. (Clin. Pharmacol. Ther., 47, 540 (1990)) describe the combination of naproxen and methotrexate as safe, although concurrent administrations of methotrexate with other NSAIDs have been reported to be toxic and sometimes fatal. A combination of a dual 5-lipoxygenase/cyclooxygenase inhibit-or with a glucocorticoid is described for the treatment of skin disorders (K. Tramposch, Inflammation, 17, 531 (1993)). Combinations of NSAIDs and steroids should be used in the treatment of scleritis only if patients are not responsive to any other treatment (S. Lightman and P. Watson, Am. J. Ophthalmol., 108, 95 (1989)). Combinations of cyclooxygenase inhibitors, lipoxygenase inhibitors, collagenase inhibitors and cytotoxic agents have been used in the treatment of non-small-cell lung cancers (B. Teicher et al., Cancer. Chemother. Pharmacol., 33, 515 (1994)). Combinations of naproxen with other NSAIDs have been described in the treatment of arthritis. R. Willikens and E. Segre (Arthritis Rheum., 19, 677 (1976)) describe the combination of aspirin and naproxen as being more effective than aspirin alone for the treatment of rheumatoid arthritis. Naproxen and acetaminophen together were described for treating the pain associated with arthritis (P. Seideman et al., Acta Orthop. Scand., 64, 285 (1993)). However, combinations of naproxen with indomethacin or ibuprofen offer no advantage in the treatment of arthritis (M. Seifert and C. Engler, Curr. Med. Res. Opin., 7, 38 (1980)).
Tenidap has been described as inhibiting cyclooxygenases and cytokine-modifying [F. Breedveld, Scand. J. Rheumatol., 23 (Supp. 100), 31 (1994)]. WO patent Publication 94/02448, published Feb. 3, 1994, describes hydroxamic acid derivatives as dual 5-lipoxygenase and cyclooxygenase inhibitors having immunosuppressant utility. U.S. Pat. No. 4,595,699, to Terada et al., describes phenyl alkanoic acid derivatives as having analgesic, antiinflammatory and immune regulating activity. R. Bartlett et al. describe thiazolo(3,2-b)(1,2,4)triazin-7-ones as antiinflammatory agents with immunomodulating properties [Drugs Exptl. Clin. Res., 15, 521 (1989)]. J. Shaw and R. Greatorex [Adv. Prostaglandin, Thromboxane, Leukotriene Res., 13, 219 (1985)] describe that whereas aspirin and sodium salicylate prolong graft survival, a cyclooxygenase inhibitor reduced the survival period. V. Fimiani, et al. describe some NSAID's that may have activity in the treatment of autoimmune diseases [EOS-Revista di Immunologia and Immunofarmacologia, 13, 58 (1993)]. A. Badger et al. describe an indomethacin enhancement of suppressor cell population [Immunopharm., 4, 149 (1982)]. J. Shelby et al. [Transplantation Proc., 19, 1435 (1987)] describe indomethacin as reversing transfusion-induced graft prolongation. D. Latter et al. indicate that indomethacin was effective as an immunomodulator following burns [J. Surg. Res., 43, 246 (1987)]. J. Tarayre et al. describe indomethacin as having an effect in their delayed hypersensitivity models [Arzneim.-Forsch./Drug Res., 40, 1125 (1990)]. D. Braun et al indicate that a prostaglandin synthetase inhibitor may help prevent chemotherapy-induced decline in immune reactivity [Proc. Am. Soc. Clin. Oncol., 4, 21 Meeting, 223 (1985)]. Administration of tepoxalin (dual 5-LO and COX inhibitor) and cyclosporine has been described [Fung-Leung, et al., Transplantation, 60, 362 (1995)] in suppression of graft versus host reaction although the effect of tepoxalin did not appear to be related to the inhibition of arachidonic acid metabolism.
There have been no reported combinations of a cyclooxygenase-2 selective inhibitor and a leukotriene B.sub.4 receptor antagonist as having a significant prolongation of graft survival.